Project Summary. Calorie restriction (CR) is a dietary regimen that extends the mean and maximum lifespan of multiple organisms ranging from yeast to mammals. In mammals, CR also protects against aging-associated diseases such as cancer and type 2 diabetes, and is therefore considered to improve ?health span? during the aging process. Following a long-term CR diet is difficult for humans maintain, so there ha been tremendous interest in development and characterization of small molecule neutraceuticals or drugs that can mimic the beneficial effects of CR on physiology and health span without the negative side effects. The budding yeast, Saccharomyces cerevisiae, is a popular genetic system for studying aging and has been instrumental in developing some of the paradigms in aging research, including the involvement of sirtuins, TOR signaling, and autophagy. CR in yeast is modeled by simply reducing the glucose concentration in the growth medium from 2% to 0.5% (or less), which causes an increase in both the replicative lifespan (RLS), defined as the number of times a mother cell can divide, and chronological lifespan (CLS), defined as the number days that cells remain viable in a non-dividing state. We have discovered that the expired media from calorie restricted CLS cultures contains one or more unknown small molecules that can be concentrated as a crude extract and then added back to non-restricted yeast cells to extend CLS. Saccharomyces cerevisiae is a natural food source for fruit flies (Drosophila melanogaster), and a standard component of fly food in the lab. Interestingly, the crude longevity factor(s) also extends fly lifespan when supplemented into their food, suggesting the existence of a natural trans-kingdom mechanism of caloric restriction between these organisms. Therefore, the main goals of this research project are to identify the active compound or compounds from the crude expired media that are responsible for yeast and fly lifespan extension, and to begin characterizing the generality and mechanism of this novel interaction.